This invention relates generally to fluid handling, and more particularly to apparatus and methods for fluid manifolds in gas turbine engines.
A gas turbine engine includes a turbomachinery core having a high pressure compressor, a combustor, and a high pressure turbine in serial flow relationship. The core is operable in a known manner to generate a primary gas flow. Depending on the engine's configuration, the core may be combined with a fan and low pressure turbine system to generate propulsive thrust, or with a work turbine to extract mechanical energy and turn a driveshaft or propeller.
In conventional gas turbine engines, fuel is introduced to the combustor through an array of fuel nozzles which are coupled to an external manifold surrounding the combustor. In operation, pressurized fuel is fed to the manifold. The manifold then distributes the pressurized fuel to the individual fuel nozzles. Such manifolds are commonly manufactured from various tubes and fittings, and are secured to the combustor with brackets and other mounting hardware. Such manifolds experience significant vibration during engine operation.
Thermal growth is a critical design criterion for these fuel manifolds. The cases that support the fuel nozzles grow as the engine warms, but the temperature of the fuel in the manifold stays relatively cool. This temperature difference, coupled with the different material growth rates of various components, creates a thermal loading on the manifold. To avoid fatigue failure, the manifold's properties such as stiffness, damping, etc. must be designed so as to avoid excitation of one or more of the manifold's natural frequencies within the engine operating range while providing proper flexibility for thermal growth.
These manifolds are unique to each specific engine model. This requires a substantial design effort and testing iterations, leading to high engineering costs. Furthermore, the typical geometry and large part count leads to relatively high system weights.